1. Field of the Invention
The invention is directed to a seal guide unit for guiding and sealing a piston rod of a vibration damper in a motor vehicle.
2. Description of the Prior Art
A seal guide unit of this type is known, for example, from DE8201327U1. It comprises a first guide element and a second guide element fixedly connected to the first guide element and arranged coaxial to the first guide element with respect to a center axis of the seal guide unit. A radially moveable piston rod seal is arranged between the two guide elements coaxial to the two guide elements and is directly surrounded in circumferential direction by the upper guide element referring to the sole figure. The piston rod seal comes in direct axial contact with the upper guide element and at least in indirect axial contact with the lower guide element via a further component part.
It is an object of a seal guide unit that a piston rod penetrating into a damper tube of a vibration damper is to be positioned radially relative to the damper tube and the piston rod is to be guided when moving into the damper tube and when moving out of the damper tube and a tilting of the piston rod relative to the damper tube is accordingly to be prevented. Because the vibration dampers generally contain a liquid or gaseous damping medium in the interior of the damper tube, the piston rod should be sealed to prevent the uncontrolled escape of damping medium from the cylinder tube. This task is taken over by the piston rod seal. If the vibration damper is employed at different outside temperatures, the above-described tightness can be ensured only with great difficulty. At very low temperatures, the elasticity of the piston rod seal possibly declines very severely. When a lateral load is introduced, the piston rod makes a minimal radial displacement and is minimally radially deformed. Because of the reduced elasticity, the piston rod seal cannot follow this radial path of the piston rod or return to the original shape fast enough. Accordingly, the development of leakiness at low temperatures cannot be prevented.
DE 199 30 964 A1 discloses a piston rod seal arranged in the seal guide unit so as to be radially moveable and which can accordingly follow a radial movement of the piston rod. A disadvantage of this design is that it is very complicated and comprises many individual parts, which makes assembly considerably more difficult and necessitates an increased assembly time.